System and method for treatment of pain related to limb joint replacement surgery

ABSTRACT

It has been discovered that pain felt in a given region of the body can be treated by stimulating a peripheral nerve at a therapeutically effective distance from the region where pain is felt to generate a comfortable sensation (i.e., paresthesia) overlapping the regions of pain. A method has been developed to reduce pain in a painful region following limb joint replacement by stimulating a peripheral nerve innervating the painful region with an electrode inserted into tissue and spaced from the peripheral nerve. This method may be used to help alleviate postoperative pain in patients following total knee arthroplasty surgery or other limb joint replacement surgeries.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.16/391,362, entitled “System and Method for Treatment of Pain Related toLimb Joint Replacement Surgery,” filed on Apr. 23, 2019 which is acontinuation of U.S. application Ser. No. 15/419,038, entitled “Systemand Method for Treatment of Pain Related to Limb Joint ReplacementSurgery,” filed on Jan. 30, 2017, which is a continuation of U.S.application Ser. No. 14/547,493, entitled “System and Method forTreatment of Pain Related to Limb Joint Replacement Surgery,” filed onNov. 19, 2014, now U.S. Pat. No. 9,555,245, which is a continuation ofU.S. application Ser. No. 13/791,710 entitled “System and Method forTreatment of Pain Related to Limb Joint Replacement Surgery” filed onMar. 8, 2013, now U.S. Pat. No. 8,965,516, which claims the benefit fromU.S. Provisional Patent Application No. 61/608,106 entitled “Systems andMethods for Bodily Conditioning and Treatment of Pain Related toSurgery” filed on Mar. 8, 2012, which are all hereby incorporated intheir entirety by reference.

FIELD OF INVENTION

The present invention generally relates to a system and a method todeliver electrical stimulation to treat post-operative pain followinglimb joint replacement surgery.

BACKGROUND OF THE INVENTION

Limb joint replacement surgery is often able to provide patients with aremarkable improvement in their health. However, these surgeries oftenrequire significant rehabilitation often eliminating it as a treatmentalternative for patients. Moreover, the pain associated with thesesurgeries can cause a delay in rehabilitation potentially reducing theefficacy of such treatments. In order for patients to beginrehabilitation promptly to increase the likelihood of success of suchsurgeries, it is imperative that the pain following the limb jointreplacement surgery be managed.

While existing systems and techniques can offer some relief andancillary benefits to individuals requiring therapeutic relief, manyissues and the need for improvements still remain. For example,non-narcotic analgesics, such as acetaminophen or non-steroidalanti-inflammatory drugs (NSAIDS), have relatively minor side effects andare commonly used for several types of pain. However, they are rarelysufficient in managing moderate to severe postoperative pain.

The use of narcotic analgesics, such as opioids, has shown only minorsuccess with inconsistent results. Narcotics carry the risk of addictionand side effects, such as constipation, nausea, confusion, vomiting,hallucinations, drowsiness, dizziness, headache, agitation, andinsomnia. Further, narcotics may impair a patient's ability to undergorehabilitation.

Electrical stimulation systems have been used for the relief of chronicpain, but widespread use of available systems for the treatment ofpostoperative pain is limited. There exist both external and implantabledevices for providing electrical stimulation to activate nerves and/ormuscles to provide therapeutic relief of pain. These “neurostimulators”are able to provide treatment and/or therapy to individual portions ofthe body. The operation of these devices typically includes the use ofan electrode placed either on the external surface of the skin or asurgically implanted electrode. In most cases, surface electrode(s),cuff-style electrode(s), paddle-style electrode(s), or spinal columnelectrodes may be used to deliver electrical stimulation to the selectportion of the patient's body.

One example of the neurostimulators identified above is transcutaneouselectrical nerve stimulation (TENS). TENS has been cleared by the FDAfor treatment of pain. TENS systems are external neurostimulationdevices that use electrodes placed on the skin surface to activatetarget nerves below the skin surface. TENS has a low rate of seriouscomplications.

Application of TENS has been used to treat pain with inconsistentresults, and it has low patient compliance, because it may causeadditional discomfort by generating cutaneous pain signals due to theelectrical stimulation being applied through the skin. Additionally, theoverall system is bulky and cumbersome. Further, TENS requires thatsurface electrodes be placed near the site of pain, which would be nearthe incision site for post-operative pain. This may impair healing orincrease the risk of infection for the patient.

Moreover, several clinical and technical issues associated with surfaceelectrical stimulation have prevented it from becoming a widely acceptedtreatment method. First, stimulation of cutaneous pain receptorsoftentimes cannot be avoided resulting in stimulation-induced pain thatlimits patient tolerance and compliance. Second, it is difficult tostimulate deep nerves and/or muscles with surface electrodes withoutstimulating overlying, more superficial nerves and/or muscles resultingin unwanted stimulation. Finally, clinical skill and intensive patienttraining is required to place surface electrodes reliably on a dailybasis and adjust stimulation parameters to provide optimal treatment.The required daily maintenance and adjustment of a surface electricalstimulation system is a major burden on both patient and caregiver.

Peripheral nerve stimulation may be effective in reducing pain, but itpreviously required specialized surgeons to place cuff- or paddle-styleleads around the nerves in a time consuming procedure. This isparticularly problematic to treat post-operative pain in that additionalsurgeries may be required to actually treat the pain—typically not apreferred approach, especially to treat pain following a separatesurgery.

These above-mentioned methods of implementation have practicallimitations that prevent widespread use.

Nevertheless, undergoing a surgical procedure, and recovering therefrom,is generally a painful process, emotionally and physically. Thereremains room in the art of surgical preparation and/or pain managementfor improved systems and methods to be used to ready an animal body forsurgery and/or to assist in the recovery of the body after a surgicaloperation. There is, therefore, a need from an improved pain treatmentsystem and method for relief of post-operative pain, especially painfollowing limb joint replacement surgery.

SUMMARY OF THE INVENTION

The invention provides systems and methods for placing one or more leadsin tissues for providing electrical stimulation to tissue to treat painin a manner unlike prior systems and methods.

The invention provides an electrical stimulation device having at leastone percutaneous lead adapted for insertion within tissue of an animalbody and a pulse generator operatively coupled with the at least onelead, wherein the pulse generator is configured to stimulate at leastone nerve innervating a region of pain following the limb jointreplacement surgery.

The invention further provides a kit for treatment of pain followinglimb joint replacement surgery having a needle insertable into an animalbody tissue, at least one percutaneous electrode lead operativelyinserted into the needle, wherein the needle and at least onepercutaneous lead are inserted into an insertion point of the animalbody, whereby the needle is removable from the animal body tissue andthe at least one percutaneous electrode lead is retained within theanimal body, and a pulse generator operatively coupled with the at leastone electrode lead, wherein the pulse generator is configured tostimulate at least one nerve innervating a region of pain following alimb joint replacement surgery.

The invention also provides methods to alleviate pain following a limbjoint replacement surgery including inserting at least one electrodewithin a therapeutically effective distance from at least one nerve, andapplying electrical stimulation through the at least one electrode toaffect the at least one nerve innervating a region of pain following thelimb joint replacement surgery, wherein the electrical stimulation doesnot cause pain.

Other features and advantages of the inventions are set forth in thefollowing specification and attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Operation of the invention may be better understood by reference to thedetailed description taken in connection with the followingillustrations, wherein:

FIGS. 1A and 1B are schematic anatomic views, respectively anterior andlateral, of a human peripheral nervous system.

FIG. 2 is a schematic anatomic view of a human spine, showing thevarious regions and the vertebrae comprising the regions.

FIG. 3 is an anatomic view of the spinal nerves of the lumbar plexus.

FIG. 4 is an anatomic view of the spinal nerves of the sacral plexus.

FIG. 5 is an anatomic view of the femoral nerve and sciatic nerveinnervation of the leg.

FIGS. 6A to 6C are views showing a percutaneous lead that can form apart of a peripheral nerve stimulation system.

FIG. 7 is a view of a package containing a peripheral nerve stimulationsystem.

FIGS. 8A/B and 9A/B are representative leads that can form a part of aperipheral nerve stimulation system.

FIGS. 10A and 10B are schematic anatomic views of a system for applyingperipheral nerve stimulation to a femoral nerve.

FIGS. 11A and 11B are schematic anatomic views of a system for applyingperipheral nerve stimulation to a sciatic/tibial nerve.

FIGS. 12A and 12B are schematic sectional anatomic views of systems forapplying peripheral nerve stimulation to a femoral nerve and asciatic/tibial nerve.

FIGS. 13A, 13B, and 13C are schematic sectional anatomic views of asystem for applying peripheral nerve stimulation along a sciatic/tibialnerve.

FIG. 14 is a frontal view showing the peripheral nerve stimulationsystem and TKA incision.

FIGS. 15A, 15B, 15C, and 15D are idealized, diagrammatic view showingperipheral nerve stimulation systems.

FIG. 16 is a view of the areas of pain and paresthesia on a diagram ofthe body.

DETAILED DESCRIPTION

Reference will now be made in detail to exemplary embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. It is to be understood that other embodiments may be utilizedand structural and functional changes may be made without departing fromthe respective scope of the invention. Moreover, features of the variousembodiments may be combined or altered without departing from the scopeof the invention. As such, the following description is presented by wayof illustration only and should not limit in any way the variousalternatives and modifications that may be made to the illustratedembodiments and still be within the spirit and scope of the invention.

Any elements described herein as singular can be pluralized (i.e.,anything described as “one” can be more than one). Any species elementof a genus element can have the characteristics or elements of any otherspecies element of that genus. The described configurations, elements orcomplete assemblies and methods and their elements for carrying out theinvention, and variations of aspects of the invention can be combinedand modified with each other in any combination.

I. The Peripheral Nervous System—Anatomic Overview

As generally shown in FIGS. 1A and 1B, the peripheral nervous systemconsists of nerve fibers and cell bodies outside the central nervoussystem (the brain and the spinal column) that conduct impulses to oraway from the central nervous system. The peripheral nervous system ismade up of nerves (called spinal nerves) that connect the centralnervous system with peripheral structures. The spinal nerves of theperipheral nervous system arise from the spinal column and exit throughintervertebral foramina in the vertebral column (spine). The afferent,or sensory, fibers of the peripheral nervous system convey neuralimpulses to the central nervous system from the sense organs (e.g., theeyes) and from sensory receptors in various parts of the body (e.g., theskin, muscles, etc.). The efferent, or motor, fibers convey neuralimpulses from the central nervous system to the effector organs (musclesand glands).

The somatic nervous system (SNS) is the part of the peripheral nervoussystem associated with the voluntary control of body movements throughthe action of skeletal muscles, and with reception of external stimuli,which helps keep the body in touch with its surroundings (e.g., touch,hearing, and sight). The system includes all the neurons connected withskeletal muscles, skin and sense organs. The somatic nervous systemconsists of efferent nerves responsible for sending central nervoussignals for muscle contraction. A somatic nerve is a nerve of thesomatic nervous system.

A. Spinal Nerves

A typical spinal nerve arises from the spinal cord by rootlets whichconverge to form two nerve roots, the dorsal (sensory) root and theventral (motor) root. The dorsal and ventral roots unite into a mixednerve trunk that divides into a smaller dorsal (posterior) primary ramusand a much larger ventral (anterior) primary ramus. The posteriorprimary rami serve a column of muscles on either side of the vertebralcolumn, and a narrow strip of overlying skin. All of the other muscleand skin is supplied by the anterior primary rami.

The nerve roots that supply or turn into peripheral nerves can begenerally categorized by the location on the spine where the roots exitthe spinal cord, i.e., as generally shown in FIG. 2, cervical (generallyin the head/neck, designated C1 to C8), thoracic (generally inchest/upper back, designated T1 to T12), lumbar (generally in lowerback, designated L1 to L5); and sacral (generally in the pelvis,designated S1 to S5). All peripheral nerves can be traced back(proximally toward the spinal column) to one or more of the spinal nerveroots in either the cervical, thoracic, lumbar, or sacral regions of thespine. The neural impulses comprising pain felt in a given muscle orcutaneous region of the body pass through spinal nerves and (usually)one or more nerve plexuses. The spinal nerves begin as roots at thespine, and can form trunks that divide by divisions or cords intobranches that innervate skin and muscles.

B. Nerves of the Sacral Plexus

The sacral plexus provides motor and sensory nerves for the posteriorthigh, most of the lower leg, and the entire foot.

1. The Sciatic Nerve

As shown in FIGS. 1A and 4, the sciatic nerve (also known as theischiatic nerve) arises from the sacral plexus. It begins in the lowerback and runs through the buttock and down the lower limb. The sciaticnerve supplies nearly the whole of the skin of the leg, the muscles ofthe back of the thigh, and those of the leg and foot. It is derived fromspinal nerves L4 through S3. It contains fibers from both the anteriorand posterior divisions of the lumbosacral plexus.

The nerve gives off articular and muscular branches. The articularbranches (rami articulares) arise from the upper part of the nerve andsupply the hip-joint, perforating the posterior part of its capsule;they are sometimes derived from the sacral plexus. The muscular branches(rami musculares) innervate the following muscles of the lower limb:biceps femoris, semitendinosus, semimembranosus, and adductor magnus.The nerve to the short head of the biceps femoris comes from the commonperoneal part of the sciatic, while the other muscular branches arisefrom the tibial portion, as may be seen in those cases where there is ahigh division of the sciatic nerve.

The muscular branch of the sciatic nerve eventually gives off the tibialnerve (shown in FIG. 1A) and common peroneal nerve (also shown in FIG.1A), which innervates the muscles of the (lower) leg. The tibial nerveinnervates the gastrocnemius, popliteus, soleus and plantaris musclesand the knee joint. It also goes on to innervate all muscles of the footexcept the extensor digitorum brevis (which is innervated by theperoneal nerve).

C. Nerves of the Lumbar Plexus

The lumbar plexus (see FIG. 3) provides motor, sensory, and autonomicfibers to gluteal and inguinal regions and to the lower extremities. Thegluteal muscles are the three muscles that make up the buttocks: thegluteus maximus muscle, gluteus medius muscle and gluteus minimusmuscle. The inguinal region is situated in the groin or in either of thelowest lateral regions of the abdomen.

1. The Iliohypogastric Nerve

The iliohypogastric nerve (see FIG. 3) runs anterior to the psoas majoron its proximal lateral border to run laterally and obliquely on theanterior side of quadratus lumborum. Lateral to this muscle, it piercesthe transversus abdominis to run above the iliac crest between thatmuscle and abdominal internal oblique. It gives off several motorbranches to these muscles and a sensory branch to the skin of thelateral hip. Its terminal branch then runs parallel to the inguinalligament to exit the aponeurosis of the abdominal external oblique abovethe external inguinal ring where it supplies the skin above the inguinalligament (i.e. the hypogastric region) with the anterior cutaneousbranch.

2. The Ilioinguinal Nerve

The ilioinguinal nerve (see FIG. 3) closely follows the iliohypogastricnerve on the quadratus lumborum, but then passes below it to run at thelevel of the iliac crest. It pierces the lateral abdominal wall and runsmedially at the level of the inguinal ligament where it supplies motorbranches to both transversus abdominis and sensory branches through theexternal inguinal ring to the skin over the pubic symphysis and thelateral aspect of the labia majora or scrotum.

3. The Lateral Cutaneous Femoral Nerve

The lateral cutaneous femoral nerve (see FIG. 3) pierces psoas major onits lateral side and runs obliquely downward below the iliac fascia.Medial to the anterior superior iliac spine it leaves the pelvic areathrough the lateral muscular lacuna. In the thigh it briefly passesunder the fascia lata before it breaches the fascia and supplies theskin of the anterior thigh.

4. The Obturator Nerve

The obturator nerve (see FIG. 3) leaves the lumbar plexus and descendsbehind psoas major on it medial side, then follows the linea terminalisand exits through the obturator canal. In the thigh, it sends motorbranches to obturator externus before dividing into an anterior and aposterior branch, both of which continue distally. These branches areseparated by adductor brevis and supply all thigh adductors with motorinnervation: pectineus, adductor longus, adductor brevis, adductormagnus, adductor minimus, and gracilis. The anterior branch contributesa terminal, sensory branch which passes along the anterior border ofgracilis and supplies the skin on the medial, distal part of the thigh.

5. The Femoral Nerve

The femoral nerve (see FIG. 3 and also FIG. 10A) is the largest andlongest nerve of the lumbar plexus. It gives motor innervation toiliopsoas, pectineus, sartorius, and quadriceps femoris; and sensoryinnervation to the anterior thigh, posterior lower leg, and hindfoot. Itruns in a groove between psoas major and iliacus giving off branches toboth muscles. In the thigh it divides into numerous sensory and muscularbranches and the saphenous nerve, its long sensory terminal branch whichcontinues down to the foot.

The femoral nerve has anterior branches (intermediate cutaneous nerveand medial cutaneous nerve) and posterior branches. The saphenous nerve(branch of the femoral nerve) provides cutaneous (skin) sensation in themedial leg. Other branches of the femoral nerve innervate structures(such as muscles, joints, and other tissues) in the thigh and around thehip and knee joints. As an example, branches of the femoral nerveinnervate the hip joint, knee joint, and the four parts of theQuadriceps femoris (muscle): Rectus femoris (in the middle of the thigh)originates on the ilium and covers most of the other three quadricepsmuscles. Under (or deep to) the rectus femoris are the other 3 of thequadriceps muscles, which originate from the body of the femur. Vastuslateralis (on the outer side of the thigh) is on the lateral side of thefemur. Vastus medialis (on the inner part thigh) is on the medial sideof the femur. Vastus intermedius (on the top or front of the thigh) liesbetween vastus lateralis and vastus medialis on the front of the femur.Branches of the femoral nerve often innervate the pectineus andsartorius muscles.

II. The System

Shown in FIG. 7 is an electrical stimulation device 164 configured totreat post-operative pain, especially pain following limb jointreplacement surgery. Here, a limb joint replacement surgery is definedto include a shoulder, elbow, wrist, finger joint, hip, knee, ankle andtoe joint, but to exclude the back, neck and head. The electricalstimulation device may include one or more leads 12 having one or moreelectrodes 14 adapted for insertion into in any tissue of the body inelectrical proximity but away from nerves. This location of leads 12 mayimprove recruitment of targeted nerves for therapeutic purposes, such asfor the treatment of pain. It is to be appreciated that the presentelectrical stimulation device is intended only to treat regions of painthat include any limbs or joint replacements, including arms and legs inboth humans and animals.

A. Stimulation of Peripheral Nerves

FIGS. 15A-15D show a peripheral nerve system and method thatincorporates features of the present teachings. As shown in FIGS.15A-15D, the system and method may identify a region where there is alocal manifestation of pain. The region of pain may comprise anyappropriate portion of the body, e.g., tissue, skin, bone, a joint, ormuscle. The system and method may identify one or more spinal nerveslocated distant from the region where pain is manifested, through whichneural impulses comprising the pain pass. A given spinal nerve that isidentified may comprise a nerve trunk located in a nerve plexus, or adivision and/or a cord of a nerve trunk, or a nerve branch, or a nerveplexus provided that it is upstream or cranial of where the nerveinnervates the region affected by the pain. The given spinal nerve maybe identified by medical professionals using textbooks of human anatomyalong with their knowledge of the site and the nature of the pain orinjury, as well as by physical manipulation and/or imaging, e.g., byultrasound, fluoroscopy, or X-ray examination, of the region where painis manifested. A desired criteria of the selection may includeidentifying the location of tissue in a therapeutically effectivedistance from the nerve or passage, which tissue may be accessed byplacement of one or more stimulation electrodes, aided if necessary byultrasonic or electro-location techniques. A therapeutically effectivedistance may be defined to mean the placement of a lead either incontact with, or more preferably adjacent to a nerve. The nerveidentified may comprise a targeted peripheral nerve. The tissueidentified may comprise the “targeted tissue.”

The electrodes 14 of the electrical stimulation device 164 may bepercutaneously inserted using percutaneous leads 12. The system andmethod may place the one or more leads 12(B) with its electrode 14(B) inthe targeted tissue in electrical proximity to but spaced away from thetargeted peripheral nerve. The system and method may apply electricalstimulation through the one or more stimulation electrodes 14(B) toelectrically activate or recruit the targeted peripheral nerve thatconveys the neural impulses comprising the pain to the spinal column.

The system and method may apply electrical stimulation to peripheralnerves throughout the body. By way of a non-limiting example, theperipheral nerves may comprise one or more spinal nerves in the brachialplexus, to treat pain in the shoulders (see FIG. 15C), arms and hands(see FIG. 15D); and/or one or more spinal nerves in the lumbar plexus,to treat pain in the thighs, knees, and calves (see FIGS. 15A and 15B);and/or one or more spinal nerves in the sacral plexus, to treat pain inthe thighs, calves, and feet (see FIGS. 15A and 15B); and/or one or morespinal nerves in the cervical plexus, to treat pain in the shoulders(see FIG. 15C).

For example, if the pinky finger is the location of pain following alimb joint replacement surgery, the system and method may identify andstimulate the ulnar nerve at a location upstream or cranial of where thenerve innervates the muscle or skin of the pinky finger, e.g., in thepalm of the hand, forearm, and/or upper arm. If electrical stimulationactivates the target peripheral nerve sufficiently at the correctintensity, then the patient will feel a comfortable tingling sensationcalled paresthesia in the same region as their pain, which overlaps withthe region of pain and/or otherwise reduce pain.

It is to be appreciated that the sensation could be described with otherwords such as buzzing, thumping, etc. Evoking paresthesia in the regionof pain confirms correct lead placement and indicates stimulus intensityis sufficient to reduce pain. Inserting a lead 12 percutaneously mayallow the lead 12 to be placed quickly and easily. Placing the lead 12in a peripheral location, i.e., tissue, where it is less likely to bedislodged, may address lead migration problems of spinal cordstimulation that may otherwise cause decreased paresthesia coverage,decreased pain relief, and the need for frequent patient visits forreprogramming.

Placing the lead 12 percutaneously in tissue in electrical proximity tobut spaced away from the targeted peripheral nerve may also minimizecomplications related to lead placement and movement. In a percutaneoussystem, an electrode lead 12, such as a coiled fine wire electrode leadmay be used because it is minimally-invasive and well suited forplacement in proximity to a peripheral nerve. The lead may be sized andconfigured to withstand mechanical forces and resist migration duringlong-term use, particularly in flexible regions of the body, such as theshoulder, elbow, and knee.

As FIG. 6A shows, the electrode lead may include a fine wire electrode14, paddle electrode, intramuscular electrode, or general-purposeelectrode, inserted via a needle introducer 30 or surgically implantedin proximity of a targeted peripheral nerve. Once proper placement isconfirmed, the needle introducer 30 may be withdrawn (as FIGS. 6B and 6Cshow), leaving the electrode 14 in place. Stimulation may also beapplied through a penetrating electrode, such as an electrode arraycomprised of any number (i.e., one or more) of needle-like electrodesthat may be inserted into the target site. In both cases, the lead maybe placed using a needle-like introducer 30, allowing the lead/electrodeplacement to be minimally invasive. In a representative embodiment, thelead 12 may include a thin, flexible component made of a metal and/orpolymer material. By “thin,” it is contemplated that the lead may not begreater than about 0.75 mm (0.030 inch) in diameter. However, thepresent teachings are not limited to such dimensions. Any appropriatelead 12 may be utilized. The lead 12 may also include one or more coiledmetal wires with in an open or flexible elastomer core. The wire may beinsulated, e.g., with a biocompatible polymer film, such aspolyfluorocarbon, polyimide, or parylene. The lead 12 may beelectrically insulated everywhere except at one (monopolar), or two(bipolar), or three (tripolar), for example, conduction locations nearits distal tip. Each of the conduction locations may be connected to oneor more conductors that may run the length of the lead and leadextension 16 (see FIG. 6C) or a portion thereof. The conductor mayprovide electrical continuity from the conduction location through thelead 12 to an external pulse generator or stimulator 28 (see FIG. 6C).

The conduction location or electrode 14 may include a de-insulated areaof an otherwise insulated conductor that may run the length of anentirely insulated electrode or a portion thereof. The de-insulatedconduction region of the conductor may be formed differently, e.g., itmay be wound with a different pitch, or wound with a larger or smallerdiameter, or molded to a different dimension. The conduction location orthe electrode 14 may include a separate material (e.g., metal or aconductive polymer) exposed to the body tissue to which the conductor ofthe wire is bonded.

The lead 12 may be provided in a sterile package 62 (see FIG. 7), andmay be pre-loaded in the introducer needle 30. Alternatively, the leadmay be introduced via the same needle that is used to inject anestheticor analgesics during peripheral nerve blocks, which are often usedpost-limb joint replacement surgery. The package 62 may take variousforms and the arrangement and contents of the package 62 may be asappropriate related to the use thereof. As shown in FIG. 7, the package62 may include a sterile, wrapped assembly. The package 62 may includean interior tray made from any appropriate material, e.g., from die cutcardboard, plastic sheet, or thermo-formed plastic material, which mayhold the contents. The package 62 may also desirably includeinstructions for use 58 regarding using the contents of the package tocarry out the lead 12 location and placement procedures, as will bedescribed in greater detail below.

The lead 12 may possess mechanical properties in terms of flexibilityand fatigue life that provide an operating life free of mechanicaland/or electrical failure, taking into account the dynamics of thesurrounding tissue (i.e., stretching, bending, pushing, pulling,crushing, etc.). The material of the electrode 14 may discourage thein-growth of connective tissue along its length or an applicable portionthereof, so as not to inhibit its withdrawal at the end of its use.However, it may be desirable to encourage the in-growth of connectivetissue at the distal tip of the electrode 14, to enhance its anchoringin tissue.

Embodiments of the lead 12 shown in FIG. 12A may include a minimallyinvasive coiled fine wire lead 12 and electrode 14. The electrode 14 mayalso include, at its distal tip, an anchoring element 48. In theillustrated embodiments, the anchoring element 48 may take the form of asimple barb or bend (see also FIG. 6C).

The anchoring element 48 may be sized and configured so that, when incontact with tissue, it takes purchase in tissue, to resist dislodgementor migration of the electrode 14 out of the correct location in thesurrounding tissue. Desirably, the anchoring element 48 may be preventedfrom fully engaging body tissue until after the electrode 14 has beencorrectly located and deployed.

Alternative embodiments of the electrode lead 12 shown in FIGS. 9A and9B may also include, at or near its distal tip or region, one or moreanchoring element(s) 70. In the illustrated embodiments, the anchoringelement 70 may take the form of an array of shovel-like paddles orscallops 76 proximal to the proximal-most electrode 14 (although apaddle 76 or paddles may also be proximal to the distal most electrode14, or may also be distal to the distal most electrode 14). The paddles76 as shown may be sized and configured so they will not cut or scorethe surrounding tissue. The anchoring element 70 may be sized andconfigured so that, when in contact with tissue, it takes purchase intissue, to resist dislodgement or migration of the electrode out of thecorrect location in the surrounding tissue (e.g., muscle 54). Theanchoring element 70 may be prevented from fully engaging body tissueuntil after the electrode 14 has been deployed. The electrode 14 may notbe deployed until after it has been correctly located during theimplantation (lead placement) process, as previously described. Inaddition, the lead 12 may include one or more ink markings 74, 75 (shownin FIG. 9A) to aid the clinician in its proper placement.

Alternatively, or in combination, stimulation may be applied through anytype of nerve cuff (spiral, helical, cylindrical, book, flat interfacenerve electrode (FINE), slowly closing FINE, etc.), paddle (orpaddle-style) electrode lead, cylindrical electrode lead, echogenicneedle (i.e., visible under ultrasound) and/or other lead that issurgically or percutaneously placed within tissue at the target site.

The lead 12 may exit through the skin and connect with one or moreexternal stimulators 28 (this approach is shown in FIG. 6C). Further,the lead 12 may be connected as needed to internal and external coilsfor RF (Radio Frequency) wireless telemetry communications or aninductively coupled telemetry to control the implanted pulse generator28. The implanted pulse generator 28 may be located some distance(remote) from the electrode 14, or an implanted pulse generator may beintegrated with an electrode(s) (not shown), eliminating the need toroute the lead subcutaneously to the implanted pulse generator.

The introducer 30 (see FIG. 6A) may be insulated along the length of theshaft, except for those areas that correspond with the exposedconduction surfaces of the electrode 14 housed inside the introducer 30.These surfaces on the outside of the introducer 30 may be electricallyisolated from each other and from the shaft of the introducer 30. Thesesurfaces may be electrically connected to a connector 64 at the end ofthe introducer body (see FIG. 6A). This may allow connection to anexternal stimulator 28 (shown in FIG. 6A) during the implantationprocess. Applying stimulating current through the outside surfaces ofthe introducer 30 may provide a close approximation to the response thatthe electrode 14 will provide when it is deployed at the currentlocation of the introducer 30.

The introducer 30 may be sized and configured to be bent by hand priorto its insertion through the skin. This may allow the physician to placethe lead 12 in a location that is not in an unobstructed straight linewith the insertion site. The construction and materials of theintroducer 30 may allow bending without interfering with the deploymentof the lead 12 and withdrawal of the introducer 30, leaving the lead 12in the tissue.

Representative lead insertion techniques will now be described to placean electrode lead 12 in a desired location in tissue in electricalproximity to but spaced away from a peripheral nerve. It is this leadplacement that may make possible the stimulation of the targeted nerveor peripheral nerves with a single lead 12 to provide pain relief.

To determine the optimal placement for the lead 12, test stimulation maybe delivered through needle electrodes. Needle electrodes may be usedbecause they may be easily repositioned until the optimal location todeliver stimulation is determined. A test needle may be used to generateparesthesia.

At least one lead(s) may be placed in tissue near a targeted peripheralnerve. The lead may be inserted via the introducer 30 in any appropriatemanner, which may be similar in size and shape to a hypodermic needle.The introducer 30 may be any size. By way of a non-limiting example, theintroducer 30 may range in size from 17 gauge to 26 gauge. Beforeinserting the introducer 30, the insertion site may be cleaned with adisinfectant (e.g., Betadine, 2% Chlorhexidine/80% alcohol, 10%povidone-iodine, or similar agent). A local anesthetic(s) may beadministered topically and/or subcutaneously to the area in which theelectrode and/or introducer will be inserted.

The position of the electrodes may be checked by imaging techniques,such as ultrasound, fluoroscopy, or X-rays. Following placement of thelead(s), the portion of the leads which exit the skin may be secured tothe skin using covering bandages and/or adhesives.

Electrical stimulation may be applied to the targeted peripheral nerveduring and after placement of the electrode. This may be used todetermine whether stimulation of the targeted peripheral nerve cangenerate comfortable sensations or paresthesia that overlap with theregion of pain and/or reduce pain.

In a percutaneous system 10 (as FIGS. 6A to 6C) shown, the lead 12 maybe percutaneously placed near the targeted peripheral nerve and exit ata skin puncture site 16. A trial or screening test may be conducted inany appropriate clinical setting (e.g., an office of a clinician, alaboratory, a procedure room, an operating room, an intensive care unit,an acute rehabilitation facility, a subacute rehabilitation facility,etc.). During the trial, the lead 12 may be coupled to an external pulsegenerator 28 and temporary percutaneous and/or surface returnelectrodes, to confirm paresthesia coverage and/or pain relief of thepainful areas.

If the clinical screening test is successful, the patient may proceed totreatment with an external pulse generator 28 (as shown in FIG. 6C) andtemporary percutaneous and/or surface return electrodes. The treatmentperiod may range from minutes to hours to days to weeks to months. Byway of a non-limiting example, the treatment period may be betweenapproximately three and 21 days.

Alternatively, a fully implanted pulse generator may be used if anexternal stimulator is considered too cumbersome for the patient.

Electrical stimulation may be applied between the lead and returnelectrodes (uni-polar mode). Regulated current may be used as a type ofstimulation, but other type(s) of stimulation (e.g., non-regulatedcurrent such as voltage-regulated) may also be used. Multiple types ofelectrodes may be used, such as surface, percutaneous, and/orimplantable electrodes. The surface electrodes may be a standard shapeor they may be modified as appropriate to fit the contour of the skin.

In embodiments of a percutaneous system, the surface electrode(s) mayserve as the anode(s) (or return electrode(s)), but the surfaceelectrode(s) may be used as the cathode(s) (active electrode(s)) ifnecessary. When serving as a return electrode(s), the location of theelectrode(s) may not be critical and may be positioned anywhere in thegeneral vicinity, provided that the current path does not cross parts ofthe body (e.g., the heart), through which stimulation could be harmful.

The electrode lead may be placed via multiple types of approaches. Byway of a non-limiting example, when the targeted peripheral nerveincludes one or more nerves of the lumbar plexus or sacral plexus, theapproach may be either a posterior (shown in FIG. 10A) or an anteriorapproach (shown in FIG. 11A). This may be similar to those used forregional anesthesia of the same targeted peripheral nerve, except thatthe approach may be used for placement through an introducer ofstimulation lead(s) in electrical proximity to but spaced away from aperipheral nerve, and not for regional anesthesia. Unlike regionalanesthesia, the approach to nerves of the lumbar plexus or sacral plexusmay not involve the application of anesthesia to the nerve, and, whenthe introducer is withdrawn, the lead(s) may be left behind to desiredstimulation of the target peripheral nerve.

In other embodiments, when the targeted peripheral nerve includes thesciatic nerve (see FIG. 12A), the introducer(s) 30 and/or lead(s) 12 maybe directed towards the sciatic nerve using a posterior approach, suchas the transgluteal approach or subgluteal approach, which are both welldescribed and commonly used in regional anesthesiology. This approachmay allow lead placement near a targeted peripheral nerve with a simple,quick (e.g., less than 10 minutes) procedure.

The landmarks for the transgluteal approach may include the greatertrochanter and the posterior superior iliac spine. The introducer 30 maybe inserted distal (e.g., approximately 2 cm to 6 cm, preferably 4 cm,in a preferred embodiment) to the midpoint between the greatertrochanter and the posterior iliac spine. As a non-limiting example ofpatient positioning, the patient may be in a lateral decubitus positionand tilted slightly forward. The landmarks for the subgluteal approachmay include the greater trochanter and the ischial tuberosity. Theintroducer may be inserted distal (e.g., approximately 2 cm to 6 cm,preferably 4 cm, in the preferred embodiment) to the midpoint betweenthe greater trochanter and the ischial tuberosity.

By way of a non-limiting example, when the targeted peripheral nerveincludes the femoral nerve (see FIG. 12A), percutaneous leads 12 may bedirected towards the femoral nerve using an anterior approach. Thelandmarks may include the inguinal ligament, inguinal crease, andfemoral artery. The subject may be in the supine position withipsilateral extremity slightly (approximately 10 to 20 degrees)abducted. The introducer may be inserted near the femoral crease butbelow the inguinal crease and approximately 1 cm lateral to the pulse ofthe femoral artery.

The size and shape of tissues, such as the buttocks, surrounding thetarget nerves may vary across subjects, and the approach may be modifiedas appropriate to accommodate various body sizes and shapes to accessthe target nerve.

Introducer placement may be guided by the individual's report ofstimulus-evoked sensations (paresthesia) as the introducer is placedduring test stimulation.

As shown in FIG. 12B, more than a single lead 12 may be placed around agiven peripheral nerve, using either an anterior approach (e.g., femoralnerve) or a posterior approach (e.g., sciatic nerve). As FIGS. 13A, B,and C show, one or more leads 12 may be placed at differentsuperior-inferior positions along a peripheral nerve and/or alongdifferent peripheral nerves.

As FIGS. 10B (anterior approach, e.g., femoral nerve) and 11B (posteriorapproach, e.g., sciatic nerve) show, the lead 12 may be coupled to anexternal pulse generator 28 worn, e.g., on a belt, for a temporarystimulation regime. In this arrangement, the lead 12 may be covered witha bandage 50, and a surface electrode 54 may serve as a returnelectrode. The external/percutaneous system shown in FIGS. 10B and 10Bmay be replaced by an implanted system using an implanted pulsegenerator 60 and tunneled leads 62. In this arrangement, the case of theimplanted pulse generator 60A may include the return electrode.

Control of the stimulator and stimulation parameters may be provided byone or more external controllers. Alternatively, a controller may beintegrated with the external stimulator. The implanted pulse generatorexternal controller (i.e., clinical programmer) may be a remote unitthat uses RF (Radio Frequency) wireless telemetry communications (ratherthan an inductively coupled telemetry) to control the implanted pulsegenerator. The external or implantable pulse generator may use passivecharge recovery to generate the stimulation waveform, regulated voltage(e.g., 10 mV to 20 V), and/or regulated current (e.g., about 10 mA toabout 50 mA). Passive charge recovery may be one method of generating abiphasic, charge-balanced pulse as desired for tissue stimulationwithout severe side effects due to a DC component of the current.

The neurostimulation pulse may by monophasic (anodic or cathodic),biphasic, and/or multi-phasic. In the case of the biphasic ormulti-phasic pulse, the pulse may be symmetrical or asymmetrical. Itsshape may be rectangular or exponential or a combination of rectangularand exponential waveforms. The pulse width of each phase may rangebetween e.g., about 0.1 μsec. to about 1.0 sec., as non-limitingexamples.

Pulses may be applied in continuous or intermittent trains (i.e., thestimulus frequency changes as a function of time). In the case ofintermittent pulses, the on/off duty cycle of pulses may be symmetricalor asymmetrical, and the duty cycle may be regular and repeatable fromone intermittent burst to the next or the duty cycle of each set ofbursts may vary in a random (or pseudo random) fashion. Varying thestimulus frequency and/or duty cycle may assist in warding offhabituation because of the stimulus modulation.

The stimulating frequency may range from e.g., about 1 Hz to about 300Hz. The frequency of stimulation may be constant or varying. In the caseof applying stimulation with varying frequencies, the frequencies mayvary in a consistent and repeatable pattern or in a random (or pseudorandom) fashion or a combination of repeatable and random patterns.

In a representative embodiment, the stimulator may be set to anintensity (e.g., 1-2 mA (or 0.1-40 mA, or 0.01-200 mA), 100-300 us (or40-1000 us, or 1-10,000 us)) sufficient to activate the targeted nerveat some distance X1 (e.g., 1 mm) away (from the targeted peripheralnerve). If the stimulus intensity is too great, it may generate muscletwitch(es) or contraction(s) sufficient to disrupt correct placement ofthe lead. If stimulus intensity is too low, the lead may be advanced tooclose to the targeted peripheral nerve (beyond the optimal position),possibly leading to incorrect guidance, nerve damage, mechanicallyevoked sensation (e.g., pain and/or paresthesia) and/or musclecontraction (i.e. when the lead touches the peripheral nerve), inabilityto activate the target nerve fiber(s) without activating non-targetnerve fiber(s), improper placement, and/or improper anchoring of thelead (e.g., the lead may be too close to the nerve and no longer able toanchor appropriately in the muscle tissue).

Patient sensation may instead be used to indicate lead location relativeto the targeted peripheral nerve as indicator(s) of lead placement(distance from the peripheral nerve to electrode contact). Anycombination of stimulus parameters that evoke sensation(s) may be used.The stimulation parameters may include, but are not limited tofrequency, pulse duration, amplitude, duty cycle, patterns of stimuluspulses, and waveform shapes. Some stimulus parameters may evoke a moredesirable response (e.g., more comfortable sensation, or a sensationthat may be correlated with or specific to the specific target nervefiber(s) within the targeted peripheral nerve. As an example, higherfrequencies (e.g., 100 Hz or 12 Hz) may evoke sensation(s) orcomfortable paresthesia(s) in the region(s) of pain or in alternatetarget region(s).

While stimulation is being applied, the lead 12 (non-limiting examplesof the lead could include a single or multi-contact electrode that isdesigned for temporary (percutaneous) or long-term (implant) use or aneedle electrode (used for in-office testing only)) may be advanced(e.g., slowly advanced) towards the targeted peripheral nerve until thedesired indicator response (e.g., patient sensation, and/or pain relief)is obtained. The intensity may then be decreased (e.g., graduallydecreased) as the lead 12 is advanced (e.g., advanced slowly) closer tothe targeted nerve until the desired indicator response(s) may beobtained at smaller intensity(ies) within a target range (e.g., 0.1-1.0mA (or 0.09-39 mA, or 0.009-199 mA), 100-300 us (or 40-1000 us, or1-10,000 us)).

In the present teachings, the electrode 14 may be placed and anchored atabout 1 millimeter to about 100 millimeters spaced from the targetnerve, more preferably from about 1 millimeter to about 50 millimetersspaced from the target nerve. The electrode may touch the nerve,however, this is sub-optimal. The electrode spacing from a targetednerve may depend on various factors, and similar stimulation settingsmay invoke different responses even if spaced at similar distances.Thus, electrode spacing from the nerve may be about 10 to about 20millimeters for one target nerve at a given stimulation intensity whilethe spacing may be about 20 to about 40 millimeters for a second targetnerve at the same stimulation intensity.

If specific response(s) (e.g., desired response(s) and/or undesiredresponse(s)) may be obtained at a range of intensities that are too low,then the lead may be located in a non-optimal location (e.g., too closeto the target nerve(s)). In such situations, therefore, the clinicianmay adjust the lead location until the appropriate responses areachieved from the patient.

The stimulus intensities may be a function of many variables. Thestimulus intensities set forth herein are meant to serve as non-limitingexamples only, and may need to be scaled accordingly. As a non-limitingexample, if electrode shape, geometry, or surface area were to change,then the stimulus intensities may need to change appropriately. Forexample, if the intensities were calculated for a lead with an electrodesurface area of approximately 20 mm², then they may need to be scaleddown accordingly to be used with a lead with an electrode surface areaof 0.2 mm² because a decrease in stimulating surface area may increasethe current density, increasing the potential to activate excitabletissue (e.g., target and non-target nerve(s) and/or fiber(s)).Alternatively, if the intensities were calculated for a lead with anelectrode surface area of approximately 0.2 mm², then the intensitiesmay need to be scaled up accordingly to be used with a lead with anelectrode surface area of 20 mm². Alternatively, stimulus intensitiesmay need to be scaled to account for variations in electrode shape orgeometry (between or among electrodes) to compensate for any resultingvariations in current density. In a non-limiting example, the electrodecontact surface area may be 0.1-20 mm², 0.01-40 mm², or 0.001-200 mm².In a further non-limiting example, the electrode contact configurationmay include one or more of the following characteristics: cylindrical,conical, spherical, hemispherical, circular, triangular, trapezoidal,raised (or elevated), depressed (or recessed), flat, and/or bordersand/or contours that are continuous, intermittent (or interrupted),and/or undulating.

Stimulus intensities may need to be scaled to account for biologicalfactors, including but not limited to patient body size, weight, mass,habitus, age, and/or neurological condition(s). As a non-limitingexample, patients that are older, have a higher body-mass index (BMI),and/or neuropathy (e.g., due to diabetes) may need to have stimulusintensities scaled higher (or lower) accordingly.

As mentioned above, if the lead is too far away from the targetedperipheral nerve, then stimulation may be unable to evoke the desiredresponse (e.g., comfortable sensation(s) (or paresthesia(s)), and/orpain relief) in the desired region(s) at the desired stimulusintensity(ies). If the lead is too close to the targeted peripheralnerve, then stimulation may be unable to evoke the desired response(s)(e.g., comfortable sensation(s) (or paresthesia(s)), and/or pain relief)in the desired region(s) at the desired stimulus intensity(ies) withoutevoking undesirable response(s) (e.g., unwanted and/or painfulsensation(s) (or paresthesia(s)), increase in pain, and/or generation ofadditional pain in related or unrelated area(s)). In some cases, it maybe difficult to locate the optimal lead placement (or distance from thetargeted peripheral nerve) and/or it may be desirable to increase therange stimulus intensities that evoke the desired response(s) withoutevoking the undesired response(s) so alternative stimulus waveformsand/or combinations of leads and/or electrode contacts may be used. Anon-limiting example of alternative stimulus waveforms may include theuse of a pre-pulse to increase the excitability of the target fiber(s)and/or decrease the excitability of the non-target fiber(s).

This stimulation may be used pre-operatively or intra-operatively tolimit or prevent post-operative pain. Those skilled in the art willrecognize that, for simplicity and clarity, the full structure andoperation of all devices and processes suitable for use with the presentteachings are not being depicted or described herein.

III. Example of a Method of Use

Following a total knee arthroplasty (“TKA”), the majority of patientsexperience moderate to severe acute pain, and a lesser number continueto experience moderate to severe subacute pain. Acute and subacutepostoperative pain may limit early functional recovery, which iscritical to full rehabilitation. The patients experience different typesof pain, including nociceptive, inflammatory, and neuropathic pain. Theknee is innervated by the femoral, lateral femoral cutaneous, obturator,and the sciatic nerves. Anesthetic block of these nerves individually oras a group may reduce acute pain following a TKA. Accordingly,electrical stimulation of nerves that innervate, or portions of whichinnervate, a portion of the body (specifically a limb or joint) toundergo limb joint replacement surgery, where such stimulation occursbefore, during and/or after limb joint replacement surgery may be usedto reduce pain and enhance recovery. In this example, if the targetedperipheral nerve includes nerves of the femoral and sciatic nervesand/or their nerve branches, the method may include:

1) Place the patient in a comfortable and/or appropriate position.

2) Ask the patient to shade their area of pain on a diagram of the body.For example, as shown in FIG. 16, the shaded areas indicate where thepatient was experiencing pain.

3) Prepare the lead insertion site with antiseptic and localsubcutaneous anesthetic (e.g., 2% lidocaine) may be used as well.

4) Locate the site of skin puncture with appropriate landmarks, such asthe inguinal crease and femoral artery (for the femoral nerve) and theinterior and lateral (ventral) to the midpoint of the line connectiongreater trochanter and ishical tuberosity (for the sciatic nerve).

5) Insert a sterile percutaneous electrode lead 12 preloaded in theintroducer needle 30 at a predetermined angle based on the landmarksused. The lead may be of any appropriate configuration, such as by wayof a non-limiting example, a single fine wire with one lead to targeteach nerve.

6) Place a surface stimulation return electrode in proximity to the leadinsertion site. The surface electrode may be placed adjacent to theinsertion site. Its position is not critical to the therapy and it maybe moved throughout the therapy to reduce the risk of skin irritation,but care should be taken to place the electrode distant from thesurgical incision to generally avoid infection.

7) Couple the lead 12 to the external pulse generator 28 and to thereturn electrode. Set the desired stimulation parameters on the externalpulse generator 28, or through a controller. Test stimulation may bedelivered using a current-regulated pulse generator, for example. Theexternal pulse generator 28 may be a battery-powered stimulator, forexample.

8) Advance the introducer slowly until the subject reports the firstevoked sensation in the region experiencing pain. Progressively reducethe stimulus amplitude and advance the introducer more slowly until thesensation can be evoked in the painful region at predetermined stimulusamplitude (e.g., 1 mA). Stop the advancement of the introducer, andincrease the stimulus amplitude in small increments (e.g., 0.1 mA) untilthe stimulation-evoked tingling sensation (paresthesia) expands tooverlay the entire region of pain. The electrode may be located at anarea to generate maximal paresthesia coverage of the religion of pain,as defined by a patient shaded diagram of the body. During stimulation,the patient is asked to estimate how much of the area of pain is coveredby paresthesia. For example, as in FIG. 16, the shaded regions indicatewhere the patient experiences paresthesia during stimulation.

9) Withdraw the introducer 30, leaving the percutaneous lead 12 inproximity but away from the target nerve. Further, a plurality of leadsmay be placed percutaneously near or approximately adjacent to thenerves innervating the regions of pain, and stimulation may be appliedto determine optimal stimulus parameters and lead locations.

10) Cover the percutaneous exit site and lead 12 with a bandage. Abandage may also be used to secure the external portion of the lead 12(or an extension cable may be used to couple the lead 12 to the externalpulse generator) to the skin. It is expected the length of time to placethe lead 12 to be less than 10 minutes, although the process may beshorter or longer.

11) The external pulse generator 28 may be programmed to 100 Hz, 15 μswith amplitude sufficient to generate maximum paresthesia coverage. Theparameter may include 100% duty cycle (for both femoral and sciatic) for24 hours per day. The stimulation may be on for the duration of theacute or subacute pain of the patient. Patients may receive thestimulation therapy for a predetermined time, such as by way of anon-limiting example, two to four weeks.

12) It is possible that stimulation intensity may need to be increasedslightly during the process due to causes such as habituation or thesubject becoming accustomed to sensation. However the need for increasedintensity may be unlikely and usually only occurs after several days toweeks to months as the tissue encapsulates and the subject accommodatesto stimulation. It is to be appreciated that the need for increasedintensity may happen at any time, which may be due to either leadmigration or habituation, but may also be due reasons ranging from nervedamage to plasticity/reorganization in the central nervous system.

13) Prior to insertion of the lead and introducer needle, a sterile testneedle may be used to deliver stimulation and determine the desired siteof insertion.

14) If paresthesia cannot be evoked with the initial lead placement,redirect the introducer 30.

15) If stimulation fails to elicit paresthesia in a sufficient region(e.g., >50%) of pain, then a second percutaneous lead (not shown) may beplaced to stimulate the nerves that are not activated by the first lead12, i.e., the nerves innervating the region of post-operative pain.

Percutaneous electrical stimulation of nerves innervating the knee asdiscussed in the example above may be used to generate paresthesia toprovide pain relief for any type of post-op pain following a limb jointreplacement surgery (e.g., immediate acute phase=0 to 3-5 days; postacute or subacute phase=3-5 days to 30 days). In this approach, onemight use the femoral and sciatic nerves, or they may also stimulate thelumbar plexus to target the femoral, obturator, and/or lateral femoralcutaneous nerves. Additionally, there may be an anterior approach aswell as a posterior approach to targeting these nerves.

An alternative embodiment may include using a needle electrode/lead andplacing it during insertion of needles used during anesthetic peripheralnerve block. Additionally, in a different embodiment the pulse trainsmay be varied, as varied pulse shapes may improve selectivity ofactivation of paresthesia-fibers versus pain fibers. Percutaneouselectrical stimulation of nerves may provide some pain relief asanesthetic block without many of its drawbacks. This therapy may beprovided as a temporary therapy or as a permanent implant. Acute painrelief may allow patients to recover sufficiently enabling them to beginrehabilitation, which is critical to regaining normal function andnatural pain relief. It is generally thought that if 50% paresthesiacoverage is achieved, then there is a 70% success rate. Oftentimes afterthe stimulation therapy, the pain will never return to the patient.

Although TKA is discussed herein, it is to be understood that thesystems and methods may be employed to condition a body before or afterany limb joint replacement surgery. While stimulation of the femoraland/or sciatic nerves should generally provide relief of pain followinga limb joint replacement surgery of the leg, more distal peripheralnerves may be targets for surgeries related to distal portions of theleg (foot, ankle surgery, e.g.). For arm/hand limb joint replacementsurgery-related pain, nerves near the brachial plexus, near or below theshoulder, elbow, or wrist may be targeted.

In peripheral nerve stimulation, the lead may be placed in a tissue bywhich the targeted nerve passes, but stimulation actually relieves painthat is felt distal (downstream) from where the lead is placed. Inperipheral nerve stimulation, the lead may be placed in a tissue that isconveniently located near a nerve trunk that passes by the lead on theway to or from the painful area. The key is that the lead may be placedin a tissue that is not the target (painful) tissue, but rather a tissuethat is located away from the painful region, which is a safer and moreconvenient location to place the lead.

Peripheral nerve stimulation may be easily used by clinicians,including, but to limited to, general surgeons, orthopedic surgeons, andanesthesiologists, who are used to placing needles deeper in the tissuenear peripheral nerves. For example, anesthesiologists are accustomed toplacing needles distant from the areas of pain to numb the areas ofpain. Anesthesiologists often already use ultrasound and theelectro-location techniques that may be needed to place leads to accessperipheral nerves. This may result in the system and method to be usedin practice with little or no training.

Peripheral nerve stimulation may provide stimulation-generatedparesthesia (that ideally overlap with the area of pain) but may notrequire evoking a muscle contraction to place the lead correctly. Thetarget regions in which pain is felt and which are targeted forgeneration of paresthesia may not be the same region in which the leadis placed. This may be useful because physicians (e.g.,anesthesiologists) who will typically be placing the lead are accustomedto using paresthesia (sensory feedback description of from the patient)to guide lead placement and tuning of stimulation parameters.

Imaging (e.g., ultrasound or an alternate imaging technique, e.g.,fluoroscopy) may be used to improve lead placement near peripheralnerves. Ultrasound may improve lead placement in the form of increasingthe total speed of the procedure. Specifically, ultrasound may shortenthe procedure's duration by locating the lead in a more optimallocation. Doing so may: improve recruitment of the target fibers in thetarget nerve and minimize recruitment of non-target fibers in either thetarget nerve and/or in non-target nerve(s); and minimize risk and/ordamage to the patient during placement of the lead by avoiding bloodvessels, organs, bones, ligaments, tendons, lymphatic vessels, &/orother structures that may be damaged. One reason that imaging may beuseful is that some peripheral nerves are (but do not have to be)located relatively deeply. Alternatively, fluoroscopy may be desirablyavoided, thus lessening the cost of the procedure and the risk ofradiation exposure.

In the present system and method, the patient may not need to giveverbal, written, or other type of feedback or indication of what theyfeel as the lead is being advanced towards the peripheral nerve ifimaging is used to guide lead placement. In addition, any known methodfor non-verbal communication can be used, including those used byanesthesiologists. This allows for the system to be placed in anunconscious patient, e.g., in a sedated patient or intra-operatively.However, patient feedback during lead advancement may improve leadplacement in some patients. The patient may indicate sensations duringtuning of stimulus intensity. As non-limiting examples, those sensationsreported by the patient may include first sensation (minimum stimulusintensity that evokes a sensation), level of comfort, maximum tolerablesensation, pain, qualities or descriptions of the sensations.Alternatively, if the system is used preoperatively, as there will notbe any patient feedback of post-operative pain to guide the paresthesiacoverage, the optimal coverage would be a region that is likely to bepainful following the limb joint replacement surgery (e.g., in the caseof a TKA, both the front and back of the knee).

The region in which the patient perceives stimulation-induced sensationsor paresthesia may be an important indicator of the potential success ofthe therapy. This may help screen potential candidates and may helpdetermine the appropriate stimulation parameters (including but notlimited to lead location). Further, such parameters may be adjusted sothat the region in which paresthesia is perceived overlaps with theregion of pain.

As an alternative to using perception of stimulation induced sensationsand/or paresthesia, the level of pain or change in the intensity of painduring or due to stimulation may be used to adjust stimulationparameters (including but not limited to lead location). For example, ifa patient is experiencing “very high” pain before stimulation, nosensory or motor responses are evoked and during stimulation, if thepain decreases to “low”, the system would be considered satisfactory inthe patient.

Although the embodiments of the present invention have been illustratedin the accompanying drawings and described in the foregoing detaileddescription, it is to be understood that the present invention is not tobe limited to just the embodiments disclosed, but that the inventiondescribed herein is capable of numerous rearrangements, modificationsand substitutions without departing from the scope of the claimshereafter. The claims as follows are intended to include allmodifications and alterations insofar as they come within the scope ofthe claims or the equivalent thereof.

1. A method to alleviate pain, the method comprising: placing at leastone percutaneous lead within tissue outside of an expected targetedregion of pain resulting from a limb joint replacement surgery and neara peripheral nerve innervating the expected targeted region of pain;applying electrical stimulation to the peripheral nerve using a pulsegenerator operatively coupled with the at least one lead; and evoking apost-surgical area of paresthesia without functional nerve stimulationat a motor point and without damaging the peripheral nerve.
 2. Themethod of claim 1, wherein the limb joint replacement surgery comprisesa total knee arthroplasty.
 3. The method of claim 1, wherein the limbjoint replacement surgery comprises, total and partial limb jointreplacement, and is selected from a group consisting of: a shoulder,elbow, wrist, finger joint, hip, knee, ankle and toe joint.
 4. Themethod of claim 1, wherein the peripheral nerve is selected from a groupconsisting of a femoral nerve, a sciatic nerve, lateral femoralcutaneous nerve, and an obturator nerve.
 5. The method of claim 1further comprising: evoking a pre-surgical area of paresthesia in theexpected targeted region of pain without functional nerve stimulation ata motor point and without damaging the peripheral nerve, wherein thepre-surgical area of paresthesia is substantially identical with thepost-surgical area of paresthesia.
 6. The method of claim 5 furthercomprising: comparing the post-surgical area of paresthesia with aregion of pain occurring after the limb joint replacement surgery. 7.The method of claim 6, wherein if the post-surgical area of paresthesiadoes not substantially match the region of pain, the method furthercomprises: placing the at least one electrode within the tissue regionnear the peripheral nerve outside of the region of pain; applyingelectrical stimulation through the at least one electrode; evoking athird area of paresthesia without functional nerve stimulation at amotor point and without damaging the peripheral nerve, wherein the thirdarea of paresthesia is different from the first area of paresthesia; andcomparing the third area of paresthesia caused by the electricalstimulation with the region of pain occurring after the limb jointreplacement surgery.
 8. The method of claim 1, wherein the electricalstimulation parameters comprises at least one of frequency, pulseduration, amplitude, duty cycle, pattern of stimulus pulses, polarity, apredetermined number of phases, and wave form shape.
 9. The method ofclaim 1, wherein the electrode is operatively coupled with a lead,whereby the lead enables movement of a joint during the evoking of thesecond area of paresthesia.
 10. A method to alleviate pain post limbjoint replacement surgery, the method comprising: placing at least oneelectrode within tissue comprising a peripheral nerve innervating atargeted region, wherein the tissue is outside of the targeted region;applying electrical stimulation to activate the peripheral nerve;evoking a tingling sensation in the targeted region in advance of thelimb joint replacement surgery; applying electrical stimulation throughthe at least one electrode after the limb joint replacement surgery; andevoking a second tingling sensation in an area of paresthesia withoutfunctional nerve stimulation at a motor point and without damaging theperipheral nerve.
 11. The method of claim 10 further comprising placingthe at least one electrode near the peripheral nerve
 12. The method ofclaim 11 further comprising comparing the area of paresthesia caused bythe electrical stimulation with a region of pain occurring after thelimb joint replacement surgery.
 13. The method of claim 12, furthercomprising: re-placing the at least one electrode within the tissueregion near the peripheral nerve; re-applying electrical stimulation;causing a second area of paresthesia; and re-comparing the second areaof paresthesia caused by the electrical stimulation with the region ofpain resulting from the limb joint replacement surgery.
 14. The methodof claim 11, wherein applying electrical stimulation after the limbjoint replacement surgery comprises a first set of electricalstimulation parameters.
 15. The method of claim 14, further comprising:applying electrical stimulation after the limb joint replacementsurgery, wherein the reapplied electrical stimulation includes a set ofsecond electrical stimulation parameters, wherein at least one of thesecond electrical stimulation parameters is different from at least oneof the first electrical stimulation parameters.
 16. The method of claim15, wherein the at least one of the second electrical stimulationparameters includes at least one of frequency, pulse duration,amplitude, duty cycle, pattern of stimulus pulses, polarity, apredetermined number of phases, and wave form shape.
 17. The method ofclaim 10, wherein the limb joint replacement surgery includes total kneearthroplasty.
 18. The method of claim 17, wherein the peripheral nerveincludes the femoral nerve.
 19. The method of claim 18, wherein theelectrode is located in tissue that is distal from the targeted region.20. A method to alleviate pain, the method comprising: placing at leastone percutaneous lead within a tissue region outside of an expectedtargeted region of pain and near a peripheral nerve innervating theexpected targeted region of pain; and evoking a post-surgical area ofparesthesia without functional nerve stimulation at a motor point andwithout damaging the peripheral nerve.